Hot air gun



Oct. 19, 1937. F. o. ALBERTSON HOT AIR GUN 2 Sheets-Sheet 1 Filed May 16, 1936 fizz wzz m fizeriiviv y W/JMW Oct. 19, 1937.

F. O. ALBERTSON HOT AIR GUN Filed May 16, 1936 2 Sheets-Sheet 2 Patented Oct. 19, 1937 UNITED STATES PATENT OFFICE 2,096,023 HOT AIR GUN Application May 16, 1936, Serial No. 80,041

Claims.

The present invention relates to hot air guns, and is pmticularly concerned with devices for providing a source of heated air under pressure in suitable volume to be used in thawing out the 5 radiators of automotivevehicles or for thawing any other parts of the vehicle, such as the lubricant in the crank case, transmission, or gear housing.

One of the objects of the invention is the provision of an improved hot air gun in which the heating element is as far from the bearings of the motor as possible, in order to prevent the destructive effect of the heat on the bearings, and to keep the motor as cool as possible.

Another object is the provision of an improved hot air gun which may be constructed by the use of a standard motor and which does not require the provision of a new and larger motor housing,

in order to adapt it to the needs of the gun.

Another object of the invention is the provision of an improved fan and heater unit, which is adapted to be placed upon a standard motor of the type used for electric sanding and polishing machines, in order to convert the device into a hot air gun.

Another object of the invention is the provision of an improved sheet metal construction for a unit of the class described, which is adapted to be constructed at a lower cost than the devices of the prior art, and which is lighter than the devices of the prior art.

Another object of the invention is the provision of an improved multi-stage centrifugal air blower for units of this type, the parts of which are constructed, so far as possible, from sheet metal so that they may be stamped out in large quantities at a low cost and the device may be placed within the reach of a vast number of purchasers by reason of its low price.

Another object is the provision of an improved hot air gun of the class described, having a plurality of diilerent accessories which adapt it to different uses in or about automotive vehicles.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the drawings, of which there are two sheets,

Fig. 1 is a side elevational view of a hot air gun constructed according to the present invention and equipped with a nozzle pipe having a curved end, adapted to be used in certain inaccessible places;

Fig. 2 is afragmentary vertical sectional view, taken on the plane of a line which is coincidental with the axis of the motor drive shaft, the shaft being shown in elevation;

Fig. 3 is a fragmentary sectional view, taken on 5 the plane of the line 3-3 of Fig. 2, looking in the direction of the arrows;

Fig. 4 is an elevational view of one of the rotatable elements of the multi-stage blower, taken on the plane of the line l-l of Fig. 2, looking in the 10 direction of the arrows, with the housing omitted;

Fig. 5 is a fragmentary view in perspective, showing the mode of securement of the vanes between the walls of the stationary and rotary elements of the multi-stage blower; 15

Fig. 6 is a'sectional view taken on the plane of the line 56 of Fig. 2, looking in the direction of the arrows, showing the mode of support of the heater element;

Fig. 7 is a fragmentary sectional view, taken 20 on a plane passing through the axis of the gun, showing the details of construction of the nozzle of the gun and the mode of attachment of the various accessories;

Fig. 8 is a sectional view, taken on the plane of 25 the line l8 of Fig. 7, looking in the direction of the arrows;

Fig. 9 is an exploded view of two accessories, the lower one comprising a flexible metallic conduit, and the upper a flattened nozzle adapted to 30 be used to replace the curved pipe of Fig. 1 when desired; and

Fig. 10 is a view in perspective, and in partial section, of one type of battle, which may be used, as shown in Fig. 1, for confining the hot air in a 35 housing into which the pipe or nozzle is projected.

The present hot air gun, which is indicated in its entirety by the numeral 20, preferably includes the motor unit 2|, the multi-stage blower unit 22,

and the heater element 23, all enclosed in a suit- 40 able housing, which comprises the original motor housing supplemented by cylindrical and conical extensions.

The motor unit 2| preferably comprises a motor of the type shown in my prior Patent, No. 45 1,954,977, issued April 17, 1934, and may correspond in all its details to the motor of that unit, with the housing I! of that unit open at the point 62.

The ventilating fan ii of the motor unit is 50 removed, and the motor housing is provided with a plurality of intake apertures 24, preferably equally spaced about its periphery adjacent the open end of the motor housing to supply the blower with suflicient air. A slight amount of 66 air, suflicient to effect a cooling of the motor, is still drawn in through the ventilating apertures 25 in the motor housing, which need not be modified in this respect, but the inlets for the multi stage blower are the inlets 24.

The motor housing 26 is preferably provided with the end wall 21, having the slots or apertures 28 for passing the air from the intake apertures 24, and supporting the anti-friction bearing assembly 29. This anti-friction bearing assembly includes the outer race 33, balls 3|, and an inner race 32, which is tubular, and which extends longitudinally of the shaft 33 and projects from the motor housing for engagement with one of the rotary units of the blower.

The blower unit 22 is preferably disposed between the heating element 23 and the motor unit 2! so as to keep the heating element as far as possible from the motor, as distinguished from other devices in which the blower is located at the other end of the motor and the motor bearing is immediately adjacent the heater element.

The blower housing may consist of a cylindrical sheet metal tube 34, which is secured bywelding or otherwise to an annulus, having a cylindrical flange 35 and a radially inwardly projecting flange 36. The latter flange is secured to the motor housing by the screw bolts 31, which pass through the flange and are threaded into the body of the housing.

The cylindrical blower housing 34 communicates with the heating element housing 38, which is preferably substantially conical in form so as to bring the air into contact with the heating element 23, which is of similar shape.

The heater housing 38 has a cylindrical attaching flange 39, through which a plurality of screw bolts 40 pass, which are threaded into the feet M of the sheet metal arms 62, but which also pass through the cylindrical housing wall 33.

The sheet metal arms 42 comprise the arms of a spider for supporting the heating element, and they are sheet metal strips with oppositely turned ends 4!, 43. The flanges 33 are secured to the bodies of the sheet metal strips 42, as shown in Fig. 6, in such manner as to makea cruciform member, at the center of which is provided a threaded bore 43 for receiving the threaded end of a screw bolt 56. l v

The heating element 23 comprises a substantially. conical porcelain body 45 which is provided with a semi-circular groove 36 which extends about the periphery of the cone 45 and progresses upward toward its apex. At the base of the porcelain body 45 it is provided with a substantially cylindrical portion 41 having a plurality of radially extending slots 58 for receiving the sheet metal arms 42. This prevents rotation of the porcelain body- 45. 3

At the apex it is provided with a centrally located oraxial bore 49, which passes the screw bolt 50 of the heater element supporting body 45 to the arms 52. The heating element 5| may comprise a helical coil of resistance wire, such as nichrome wire-of suitable size and length to receive the same voltage applied to the motor and to pass a suflicient amount of current to heat the air as desired.

The heating coil 5! has one end secured to a connector bolt 52 at the lower right portion of thevbody45, in Fig. 2, and the opposite end of. the heating coilis brought through an aperture 53 and secured to a connector 54 at the opposite 'side of the porcelain body 45. Provision is preferably made for housing the conductors leading to the heating element so that they may never be engaged by the rotary blower elements. These conductors 55 and 56 are connected to the connectors 52 and 54, respectively, and led over to the right hand side of the housing, in Fig. 2, where they pass down to the motor adjacent the wall of the blower housing 34. I

The heating element is connected in parallel with the motor and is controlled by the motor switch, so that the heating element and the motor are turned on and off together.

A sheet metal strip, such as a steel strip 51, extends from the wall of the blower housing 34 at the point 58 to the point 59 and forms a small chamber 60 for housing the conductors 55, 56. This chamber may be lined with an insulating paper strip 6l,.and the metal strip 51 is held in place by a plurality of spring steel strips 62, 63, 64, which also serve as spacers for the fixed blower elements.

The steel spacer strips 6264 are adapted to spring outward into engagement with the inner wall of the blower housing 34, and they are just long enough to fit in that wall when their end engage the partition strip 51.

The motor shaft 33 of a motor unit to be used with this heat gun preferably extends longitudinally from the motor housing 26 into the blower housing 34 and terminates just short of the heating element, supporting arms 42, where it is provided with a reduced threaded end 65 and a nut 66.

The blower unit 22 preferably comprises a plurality of stages of rotary blower elements 61, 68, 69, and includes the fixed blower elements l0, 1 I. The rotary blower elements are all similar in construction, and therefore only one of them need be described in detail.

Each one consists of a supporting wall 12, which may comprise a disc of sheet metal, such as aluminum, provided with a centrally located aperture 73 for passing the drive shaft 33. The wall 12 of the blower element 69 is clamped on the drive shaft between the end of the tubular race 32 and a sleeve 14.

The same wall of the rotary element 68 is clamped between the spools I l and I5, and the same wall of the rotary element 65 is clamped between the end 66 or its washer and the sleeve 15. The other wall 11 of each rotary element 6'l69 is similar in construction, comprising a sheet metal disc of the same size, but it is provided with an enlarged centrally located aperture 16 so as to provide an annular air conduit at this end of the rotary element, surrounding the shaft 33 and sleeve 32, or surrounding the spacer Hl|5, as the case may be.

The walls l2'l7 of the rotary blower elements 61-69 are joined together by a plurality of metal vanes 18-83. Any number of metal vanes may be used, and they are preferably disposed in involute form, comprising curves of increasing radius, extending from a point substantially tangent to the central opening 16. These vanes may consist of sheet metal strips provided with a multiplicity of sheet metal tabs or ears 84, which ears pass through apertures in the walls 12-'|l and are bent over flat against the outside of the walls 12-". Alternate ears 84 are preferably bent in opposite directions.

The vanes l883 preferably curve backwardly on the rotary elements 6169, away from the direction of rotation, as shown by the arrow 86, in Fig. 4, thereby tending to supplement the centrifugal effect of the motion of the air impelled construction to the rotary blower elements in that they also comprise a pair of discs of sheet aluminum, joined by the curved vanes 18-83, which are secured to the discs by bent ears of metal on each side of the vanes 18-83.

The fixed blower elements, however, differ in that one wall 81 is of larger size, having a diameter equal to the inside diameter of the sheet metal blower housing 22. This wall also has an enlarged aperture 88 surrounding the spool 14. The other wall 89 of the flxed blower element 1| comprises a disc of the same size as the discs 12-11, and its central aperture 98 is merely large enough to pass the sleeve 14 without contact.

The fixed blower element H is secured between the rotary blower elements 68, 89, but out of contact therewith and out of contact with the shaft. It is so secured by the edge of the wall 81, being confined between the sheet metal spacer strips 63, 64. The larger disc of the fixed blower element 18 is merely secured by being clamped between the spacer strips 82, 63, thus locating that fixed blower element between the rotary elements 81 and 88.

The spacer strips 82, 63, 84 are forced into engagement with the discs of the fixed elements 18, H by the feet I of the arms 42, the latter being secured in place by the screw bolts 48. It will thus be observed that the air may enter through the apertures 28 and slots 28 and pass through the aperture 18 into the first rotary blower element 89; thence the air is thrown outward into the space 9|, the rotary element generating a velocity head, and this air then passes in between the vanes of the fixed element 1 I The vanes 01 the fixed elements preferably curve in such a direction as to correspond to the rotary movement of the air in the housing 34, and the air passes between these vanes and out of the aperture 88 into the next rotary element 88, and soon through the blower.

Each rotary impeller of the blower adds to the velocity head of the air, and large volumes of air are drawn through the blower and impeller over the coils of the heater element 23 toward the 'nozzle of the gun. The conical housing 38 surrounding. the heater element is preferably lined with an asbestos coating 92, which is cemented to the interior with a heat resistive cement.

The conical housing 38 has a centrally located aperture 93 adapted to receive the reduced end 94 of a tube having an annular shoulder 95 which seats against the end of the gun 38. These parts may then be secured together by welding at 96 or any other convenient fastening means.

The nozzle or tube 91 of the gun is preferably adapted to be connected to any of a plurality of different accessories. For example, it is provided with an internal peripherally extending groove 98, which communicates with a longitudinally extending groove 99. The surface I88 of the interior of the nozzle 91 on each side of the groove may be substantially cylindrical and adapted to slidably receive the cylindrical reduced end I8I of the other fixtures. Each of these other fixtures, such as the curved discharge pipe I82, or the flexible metallic conduit I83, or the flat discharge nozzle I84, is provided at one end with a female joint corresponding to the male connecting joint of the nozzle 91; that is, each has the reduced cylindrical portion I 8I terminating at the annular shoulder I85 which engages the end of the nozzle. Each has an inwardly projecting lug I86 which may pass through an aperture I81 and may comprise a sheet metal member having its attaching flange secured inside the tube by a rivet I88.

The lug I88 is adapted to be slid downward in the slot 99 and to be rotated in the peripheral slot 98, to secure any of the accessories to the nozzle. The flexible metal tube I83 is provided at its opposite end with the female joint I89 corresponding substantially to the structure 98, 99, I88 at the end of nozzle 91.

Fig. 1 shows the hot air gun used in connection with a curved discharge pipe I82 for discharging air into the grease-filling aperture of a transmission II8. In order to keep as much air as possible in the housing, the pipe I82 may be provided with a baille member I I I, comprising a pair of plates II2, I I3 of sheet metal, riveted together, and provided with a centrally located aperture H4.

Each plate has a pressed cup surrounding the aperture H4 so that when the plates are joined they provide a groove for receiving the garter spring I I6 which frictionally engages the pipe I82.

It will thus be observed that I have invented an improved hot air gun in which the heating element is disposed as far as possible from the bearings of the motor and from the motor structure so as to keep the motor as cool as possible.

The present hot air gun may be constructed by the addition of a multi-stage blower unit and a heating element to one of my standard electric motors of the type used for electric sanding machines and polishing machines, and shown in my prior patent above mentioned.

All of the external parts of the nozzle end of the hot air gun are made smooth, so that there is no possibility of the gun catching on the metal parts of automotive vehicles, which might otherwise interfere with the withdrawal of the nozzle.

As the present blower unit and housing parts are preferably made of sheet metal, they may be constructed at a low cost, since they lend themselves readily to stamping operations, and thus the device may be constructed more cheaply and placed within the reach of a larger number of purchasers.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims. 7

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a hot air gun, the combination of an electric motor with a centrifugal blower unit driven by the motor shaft and enclosed in a housing secured to the motor housing, a heating element in said housing spaced from said motor by said blower unit and adapted to heat the air from said blower unit to provide a source of heated air, said heating element being supported by a plurality of sheet metal arms having laterally turned feet secured to said housing, and having centrally located radially turned flanges, each flange being secured to the body of anotherof said arms.

2. In a hot air gun, the combination of an electric motor with a centrifugal blower unit driven by the motor shaft and enclosed in a housing se-. cured to the motor housing, a heating element in said housing spaced from said motor by said blower unit and adapted to heat the air from said blower unit to provide a source of heated air, said heating element being supported by a plurality of sheet metal arms having laterally turned feet secured to said housing, and having centrally located radially turned flanges, each flange being secured to the body of another of said arms, the juncture of said arms being provided with a threaded bore, and said heating element being secured by a screw bolt threaded into said bore.

3. In a hot air gun, the combination of an electric motor with a centrifugal blower unit driven by the motor shaft and enclosed in a housing secured to the motor housing, a heating element in said housing spaced from said motor by said blower unit and adapted to heat the air from said blower unit to provide a source of heated air, said heating element being supported by a plurality of sheet metal arms having laterally turned feet secured to said housing, and having centrally located radially turned flanges, each flange being secured to the body of another of said arms, the

juncture of said arms being provided with a threaded bore and said heating element being secured by a screw bolt threaded into said bore, said heating element being mounted upon an insulating base having radially extending slots for receiving said arms.

.4. In a hot air gun, the combination of an electric motor with a centrifugal blower unit driven by the motor shaft and enclosed in a housing secured to themotor housing, a heatingv element in said housing spaced from said motor by said blower unit and adapted to heat the air from said blower unit to provide a source of heated air, said housing having a substantially conical portion surrounding said heating element terminating in a discharge pipe, said discharge pipe comprising a tubular member having a reduced cylindrical portion in said conical housing and being welded to said conical housing, said discharge pipe having an internal peripherally extending slot communicating with an anally extending slot leading to the end of said pipe.

5. In a hot air gun, the combination of an electric motor with a centrifugal blower unit driven by the motor shaft and enclosed in a housing secured to the motor housing, a heating element in said housing spaced from said motor by said blower unit and adapted to heat the air from said blower unit to provide a source of heated air, said housing having a substantially conical portion surrounding said heating element terminating in a discharge pipe, said discharge pipe comprising a tubular member having a reduced cylindrical portion in said conical housing and being welded to said conical housing, said discharge pipe hav- 'ing an internal peripherally extending slot communicating with an axially extending slot leading to the end of said pipe, and an accessory having a complementary tubular formation adapted to be received in said discharge pipe and having a lug adapted to be passed in to the peripheral slot by means of the axial slot.

FRANS 0. ALBERTSON. 

